1. Field of the Invention
The invention concerns a car seat with slack roll-up mechanism, which is released by a device in the seat, so that further belt strap cannot be rolled up anymore.
2. Description of the Invention
In vehicles in general, and especially in motor vehicles, the belt strap which is to protect and hold passengers during an accident is fastened to an anchoring on one side (in the case of three-point safety belts on two sides), whereas the other end of the belt strap is taken up by a belt roller. The recently developed automatic roll-up mechanisms permit pulling of the belt strap from the roller even when the passenger has already fastened the seat belt, so that he can move freely, e.g. can lean forward and then back again. Only in an accident, be it on impact of the vehicle in any direction or in the case of turning over, the roll-up mechanism is locked; the roll-up device is held in place through latching or locking devices, so that the belt strap cannot be pulled out further and the passenger is held in place.
These automatic roll-up mechanisms are provided in most models with a tension spring, to keep the belt strap always with light tension on the body of the passenger. This assures that the belt strap is not laid too loosely or with excess slack around the passenger. The pull of the tension spring constantly exercises a certain pressure on the body which is uncomfortable during long rides. Therefore, an electric unit has already been proposed with which the spring tension of the roll-up mechanism is suspended in the moment when the belt wearer leans back against the back of the seat. This is done technically by a press button in the back seat which is actuated when leaning back. An electric circuit is closed and the current flowing through a solenoid lets a lock engage, so that the roll of the belt roller is arrested, no further strap is rolled up, and the uncomfortable tension pressure -- especially on the chest of the passenger -- stops.
Such an electrical system is, however, connected with technical expenditures and, therefore, considerable costs, aside from sources for malfunctioning due to the complexity of the system. The aim of the invention is to improve a vehicle seat of the mentioned type, so that a dependable lock is used -- by purely mechanical means with the simplest construction -- which prevents further roll-up of the belt strap and, thus, eliminates the uncomfortable pressure on the passenger.